Sheet-metal handling apparatus



July 17, 1962 s. PIERRE SHEET-METAL HANDLING APPARATUS 2 Sheets-Sheet 1Filed May 19, 1961 July 17, 1962 s. PIERRE SHEET-METAL HANDLINGAPPARATUS 2 Sheets-Sheet 2 Filed May 19, 1961 United States atet3,044,819 Patented July 17, 1962 SHEET-METAL HANDLING APPARATUS SimonPierre, 17 Ave. des Violettes, Montfermeil, France Filed May 19, 1961,Ser. No. 111,233 Claims priority, application France May 21, 1960Cnims.l (Cl. 294-88) The conveying and hoisting of cumbersome objectsand products, for example by using travelling cranes, gantry cranes, jibcranes, hoists and the like is attended by complicated problemsconcerning notably the stowing and steadying operations involvingnecessarily long handlings and the intervention of several operators.

It is the essential object of this invention to avoid these drawbacksand tol provide to this end a gripping apparatus adapted to be used inconjunction with a hoisting and/ or conveying machine, this apparatusbeing characterized in that it comprises hook-carrying arms grouped inface to face relationship to constitute two assembiies each comprisingat least one pair of arms and one pair of parallel link-systemsconnecting said arms to a frame supporting afpower unit having itsoutput shaft coupled to a mechanism adapted to move said assembliestoward and away from each other, said frame being furthermore providedwith means for suspending it from a hoisting or Iconveying apparatus.

With these combined arrangements there is obtained an apparatus adaptedto be remote controlled from a central station for gripping a load,displacing it and iinally laying it down without necessitating anymanual intervention, but its essential advantage resides in the factthat the two assemblies cooperate with each other like jaws which, dueto the provision of the aforesaid parallel-link systems, move indirections parallel to themselves instead of travelling along curvedpaths as in conventional arrangements using jaws ulcrumed albout acommon axis. Thus, the gripping hooks have always the same inclinationirrespective of the relative spacing of the two assemblies.

Other features and advantages of this invention will appear vas thefollowing description proceeds with reference to the accompanyingdrawings, it being understood that changes in the precise embodiment ofthe invention herein disclosed may |be made within the scope of what isclaimed without departing from the spirit of the invention.

In the drawings:

FIGURE l is a perspective view showing an apparatus constructedaccording to the teachings of this invention;

FIGURE 2 is another perspective view showing the apparatus during thelifting of a stack of metal sheets or plates, the gripping larms beingdesigned dierently;

FIGURE 3 is a cross-sectional view showing a gripping arm of theapparatus illustrated in FIG. 2;

FIGURE 4 is a fragmentary perspective view of a modified embodiment ofthe 'apparatus of this invention; and

FIGURE 5 is a longitudinal section showing the coupling device providedbetween the power unit or motor and the gripping mechanism.

As illustrated in the drawings, the apparatus of this inventioncomprises arms 1, 2 and 3, 4 bent at right angles Iat their upperportions to profvide corresponding horizontal members 1a, 2a, 3a, 4a. Attheir lower ends these arms terminate with hook-like portions 5, 6 and7, 8 and are grouped in face to face relationship to constitute twoidentical assemblies. Pairs of parallel links 9 and 10, 11 and 12, 13and 14, 15 and 16, .are pivoted on the one hand on the upper portion-s1a, 2a, 3a, 4a of the arms, by means of pivot pins 26, 27, 28 and 29,and on the other'hand on a frame 17, each pair of links constituting aparallel motion system.

Mounted on the frame' 17 is an electromotor 1'8 rotatably drivingthrough a coupling device to be described presently with reference toFIG. Sfa screw 19, a' reducing gear also acting as a stress limiter aswill be explained presently. Engaging the screw 19 is a nut-formingsocket 21 provided with ears 22 on which are pivotally mountedrelatively short links 23, 24 each connected toan arm and parallel-linkassembly. The short links 23, 24 are pivotally attached to pairs `ofdivergent arms 23a, 2317 and 24a, 24b respectively, the outer ends ofthese divergent arms being welded -by pairs on cylindrical hollowsleeves 3S, 36. These sleeves engage respectively cylindrical rods 37,38 interconnecting homologous links 9, 11 and 13, 1'5 of theparallel-link systems of eac-h assembly.

The above-described apparatus can be hoisted and dis-V placed by meansof any suitable apparatus such as a hoist 39 of which the hook 4t)engagesa loop 41, the side branches 41a of this loop extending downwardsand being surrounded by coil compression springs 41b disposed betweenthe top of frame 17 and relevantV end nuts 41C. Thus, when the apparatuslifts a load, the springs 41h are compressed and may actuate electricswitch means (not shown) inserted in the energizing circuit of the motor18 to avoid any untimely or faulty operation by opening this circuitautomatically when the apparatus is loaded.

The hoist 39 is provided with a current outlet 42 fed through aconductor 43. The motor 18 is supplied with current through anothercable 44 provided wit-h a plug 45 tting in the outlet 42.

To impart a sutiicient rigidity to the apparatus, the pairs of links 9and 1110 and 12, 14 and 116, 13and 15 are interconnected through rods26, 27 and Z8, 29. For the same purpose, the rods 27, 28 receive bracingmembers 30, 31 and 32, 33 each adapted to stillen one member of theparallel-link system.

In the alternate embodiment illustrated in FIGS. 2 and 3 of the drawingsthe arms v1, 2, 3 land 4 are provided with aV plate 67 bolted thereon at68, the inner vertical edgeg67a of each plate 67 being recessed inrelation to the hook 5 and projecting somewhat from the arm face whichis to engage the load to be hoisted and conveyed. Thus, when theregistering pairs ofarms of the apparatus are moved toward each otherfor hoisting a load, the edge 67a `of each arm engage the load andprevent it ffrom moving longitudinally. In fact, it is a frequentoccurrence that the load slips and falls when the apparatus is movedhorizontally, for example by means of a gantry crane, for the loadsupported by the apparatus has a considerable inertia in relation to thetravelling hoisting uni-t of the gantry crane and therefore travels witha certain time lag, thus causing the load suspended from a cable orchain to swing more or less.

In certain applications of the apparatus of this invention, it isadvantageous to move the arms of a same assernbly toward or away fromeach other in `order to ada-pt them to loads of different dimensions,for example in the case `of stacks of metal sheets or plates whereinwooden strips separate the superposed sheets or plates. This result may-be obtained with the `embodiment illustrated in FIG. 4. In this 'casethe branches of each parallel-link system consist of a plurality of-sections pivotally interconnected about axes extending at right anglesto the sections and located in the plane of the parallel-link systemconcerned, the arms of a same assembly being interconnected throughextensible means.

Thus, as shown in FIG. 4,- the links 9, 10 are each divided into threesections 9a, 9b and 10a, 10b, 10c, and likewise the links 13 and 14, aredivided into three sections 13a, 13b, 13a and 14a, 14b, 14e. Thesections of a same link are pivotally interconnected about pinsi50, 51,52, 53, `54, 55, S6 and 57. The arms pertaining to a same assembly (1, 2onV the one hand and 3, 4 on thek 9 other hand) are interconnectedthrough cross members 58, 59 (the cross members rigid with arms 3 and 4are not shown to simplify the figure) each rigid with the ar-ms andsliding by pairs in `a sleeve 60, 61 of corresponding configuration.

When it is desired to spread apart the arms of a same assembly, theoperator acts manually upon these arms and the branches of theparallel-link systems assume for example the position shown inchain-dotted lines. The cross member `53 slides within the sleeve 60 andthe arms may be locked in this different selected position through anyknown and suitable means.

According to a `modified embodiment the upper portions 1a, 2a, 3a, 4a ofarms 1,2, 3, 4 are not secured on the rods 26, 27, 28, 29 but formedwith two holes each engaged by these rods so that the arms may slidetherealong, their axial movements being limited on one side by the linksof the parallel link systems and on the other side by the bracingmembers 30-33. Since each assembly comprises two arms mounted on theaforesaid rods 2649, the permissible range of adjustment is equal totwice the distance between the links and the -bracing members. The armsare at their minimum relative spacing when each of them engages abracing member, and at their maximum relative spacing when each of themengages the links of the parallel-link Systems.

The apparatus described hereinabove with reference to two forms ofembodiment operates as follows:

This hoisting apparatus equipped with a hoist or like device 39 and ahook 40 `is brought yabove the apparatus of this invention. The hook 40engages the loop 41 and the plug is inserted into the current outlet 42.Thus, the apparatus is brought above the load to be hoisted and/orconveyed and the motor 18 is energized -in order to rotate the screw 19in the direction corresponding to the upward travel of the socket 21, sothat the short links 23 and 24 move the rods 37, 38 toward each other.These rods cause the links of the parallel-link systems to pivot, andthus the two assemblies comprising the arms 1, 2, and 3, 4 and theirhooks are moved toward each other. On the other hand, when the motor 18and screw 19 are rotated in the opposite direction .the pairs of hooksare moved away from each other. It is Worth pointing out that the Karmsremain constantly parallel to themselves when they move outwardly orinwardly, so thatthe hooks remain horizontal and the load transported bythe apparatus is constantly supported with the same efficiency,irrespective of the degree of relative spacing of the arms.

Now reference will be made to FIG. 5 to describe the coupling deviceinterposed between the motor and the gripping mechanism. In fact, duringthe conveying of the load, for example a stack of metal sheets orplates, the

` arm assemblies 1, 2 and 3, 4 tend to move toward each other under theinfluence of the weight of this load, so that the gripping mechanismproduces a self-clamping action. This increase in the clamping forcemakes it necessary to exert a considerable torque on the motor shaftwhen releasing the load. With this device the arms and load `are safelyreleased.

In FIG. 5 the motor (not shown) drives through a set of belts 71 abell-shaped member 72 constituting the driving member of the couplingdevice. Inside this bellshaped member 72 is a ball-bearing 73 retainedin position by set screws 74, this ball-bearing being carried on theother hand by an intermediate sleeve 75 secured on the frame 17 of theapparatus by means of screws 77.

Mounted inside the sleeve 75 are a pair of ball-bearings 78, 79 carryingthe shaft 80 rigid with the screw 19. The upper end of shaft 80 projectswithin the frame 17 and has wedged thereon a handwheel 81 for manuallycontrolling the rotation of the screw 19 for example when it is desiredto release the arms by hand, in case of motor or current failure.

A disk 82 solid with the shaft 8f? carries on its outer periphery aradial lug 83 engageable by a pin 84 screwed in the bottom of thebell-shaped member 72 driven from the engine. This disk 82 constitutesthe driven member of the coupling device.

When the load has been clamped between the arms, the pin 84 contacts thelug 83 on one side thereof in order drivingly to rotate the screw 19.When it is desired to release the load, the electromotor is fed in adirection to cause the bell-shaped member 72 and therefore the pin 84 torevolve firstly alone, as the pin 84 moves away from the face of lug 83which it had previously engaged.

After the pin 84 has revolved through almost a complete revolution itengages the other face of lug 83 and the shock thus applied to the disk82 and therefore to the screw 19 releases the device instantaneously andtherefore permits the unclamping movement of the arms.

The safety feature obtained during the hoisting and conveying movements,as well as the certainty of properly holding the objects to betransported result from the weight of these objects themselves. As amatter of fact, no accidental movement of the arms away from each othercan take place due to their specific shape and to the direction in whichthe gravity forces are exerted. Even an accidental starting of the motorwill not divaricate the arms since the screw 19` is driven through beltscalculated to slip when the gravity effort exceeds a predeterminedvalue.

The apparatus according to this invention may be used for transportingrigid or semi-rigid objects, such as sheet metal stacks, steel bars,tubes, paper rolls, logs, vehicles, etc. With this apparatus, cold orhot, fragile or sturdy objects can be handled indifferently whileeliminating any risk of scoring or damaging them as frequently observedwhen conventional cable hoisting means are used.

Of course, this invention is not limited to the few forms of embodimentshown and described, as many modifications and variations may be broughtthereto without departing from the spirit and scope of the invention asset forth in the appended claims.

What I claim is:

l. A gripping apparatus comprising pivoted arms for conveying andhoisting different loads, notably sheet metal stacks, which comprises aframe, hook-carrying arms supported by said frame and grouped in face toface relationship into two assemblies, each assembly comprising at leastone pair of arms, deformable parallel-link systems pivoted on the onehand on said frame and on the other hand on each one of said arms, amotor carried by said frame, means operated from said motor for movingsaid two arm assemblies toward and away from each other in order to gripand release the load respectively, and a coupling device disposedbetween said motor and said means for moving said arm assemblies towardand away from each other, said coupling device comprising a drivingmember actuated from said motor and a driven member operating saidmeans, said driving and driven members being such that they permit afree relative rotation through an angle suflicient to cause said motor,when the coupling takes place, t0 attain under no-load conditions aspeed suicient to release the arms previously clamped on the loadtransported by the apparatus.

2. Apparatus as set forth in claim 1, comprising at least one horizontallongitudinal member on which said hook-carrying arms are slidablymounted independently of one another.

3. Apparatus as set forth in claim 2, wherein the movable sides of saidparallel-link systems are mounted on the ends of said horizontallongitudinal members on which the hook-carrying arms are slidablymounted.

4. Apparatus as set forth in claim 2, wherein each longitudinal memberis common to the homologous movable sides of the parallel-link systemsof a same assembly.

5. Apparatus as set forth in claim 1, wherein each hand control wheelmounted externallyrof said frame arm is provided with .a vertical,relatively sharp edge and rigid with said driven member. recessed fromthe relevant hookl and projecting somewhat from the arm face which is toco-act with the loads References Cited in the file 0f this Patenttobelfxranspotrted. t f th l 1 h b u 5 UNITED STATES PATENTS ppara us asse or 1n calm W erem a e shaped member rotatably driven from said motorhas ler a pin secured in its bottom, .a radial lug rigid with said2284238 Todd Ma 26 1942 driven member being adapted to be engaged on oneor 2355086 Lang Ag 1944 the ofhefsidebysaidpm 10 217323248 aegefiJan.'24, 1956 7. Apparatus as set forth in claim 1, comprising a

